Sensitivity of salivary hydrogen sulfide to psychological stress and its association with exhaled nitric oxide and affect.

Background: Hydrogen sulfide (HS) is the third gasotransmitter recently discovered after nitric oxide (NO) and carbon monoxide. Both NO and HS are involved in multiple physiological functions. Whereas NO has been shown to vary with psychological stress, the influence of stress on HS and the relationship between HS and NO are unknown. We therefore examined levels of salivary HS and NO in response to a stressful final academic exam period.

Methods: Measurements of stress, negative affect, and fraction of exhaled NO (FE), were obtained from students (N=16) and saliva was collected at three time points: low-stress period in the semester, early exam period, and late exam period. Saliva was immediately analyzed for HS with the fluorescent probe Sulfidefluor-4.

Results: HS increased significantly during the early exam period and FE decreased gradually towards the late exam period. HS, FE, negative affect, and stress ratings were positively associated with each other: as stress level and negative affect increased, values of HS increased; in addition, as FE levels decreased, HS also decreased. Asthma status did not modify these associations.

Conclusion: Sustained academic stress increases HS and these changes are correlated with NO and the experience of stress and negative affect. These findings motivate research with larger samples to further explore the interaction and function of HS and FE during psychological stress.